[XFS] Use a cursor for AIL traversal.
[deliverable/linux.git] / fs / xfs / xfs_trans_ail.c
1 /*
2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_types.h"
21 #include "xfs_log.h"
22 #include "xfs_inum.h"
23 #include "xfs_trans.h"
24 #include "xfs_sb.h"
25 #include "xfs_ag.h"
26 #include "xfs_dmapi.h"
27 #include "xfs_mount.h"
28 #include "xfs_trans_priv.h"
29 #include "xfs_error.h"
30
31 STATIC void xfs_ail_insert(struct xfs_ail *, xfs_log_item_t *);
32 STATIC xfs_log_item_t * xfs_ail_delete(struct xfs_ail *, xfs_log_item_t *);
33 STATIC xfs_log_item_t * xfs_ail_min(struct xfs_ail *);
34 STATIC xfs_log_item_t * xfs_ail_next(struct xfs_ail *, xfs_log_item_t *);
35
36 #ifdef DEBUG
37 STATIC void xfs_ail_check(struct xfs_ail *, xfs_log_item_t *);
38 #else
39 #define xfs_ail_check(a,l)
40 #endif /* DEBUG */
41
42
43 /*
44 * This is called by the log manager code to determine the LSN
45 * of the tail of the log. This is exactly the LSN of the first
46 * item in the AIL. If the AIL is empty, then this function
47 * returns 0.
48 *
49 * We need the AIL lock in order to get a coherent read of the
50 * lsn of the last item in the AIL.
51 */
52 xfs_lsn_t
53 xfs_trans_tail_ail(
54 xfs_mount_t *mp)
55 {
56 xfs_lsn_t lsn;
57 xfs_log_item_t *lip;
58
59 spin_lock(&mp->m_ail_lock);
60 lip = xfs_ail_min(mp->m_ail);
61 if (lip == NULL) {
62 lsn = (xfs_lsn_t)0;
63 } else {
64 lsn = lip->li_lsn;
65 }
66 spin_unlock(&mp->m_ail_lock);
67
68 return lsn;
69 }
70
71 /*
72 * xfs_trans_push_ail
73 *
74 * This routine is called to move the tail of the AIL forward. It does this by
75 * trying to flush items in the AIL whose lsns are below the given
76 * threshold_lsn.
77 *
78 * the push is run asynchronously in a separate thread, so we return the tail
79 * of the log right now instead of the tail after the push. This means we will
80 * either continue right away, or we will sleep waiting on the async thread to
81 * do it's work.
82 *
83 * We do this unlocked - we only need to know whether there is anything in the
84 * AIL at the time we are called. We don't need to access the contents of
85 * any of the objects, so the lock is not needed.
86 */
87 void
88 xfs_trans_push_ail(
89 xfs_mount_t *mp,
90 xfs_lsn_t threshold_lsn)
91 {
92 xfs_log_item_t *lip;
93
94 lip = xfs_ail_min(mp->m_ail);
95 if (lip && !XFS_FORCED_SHUTDOWN(mp)) {
96 if (XFS_LSN_CMP(threshold_lsn, mp->m_ail->xa_target) > 0)
97 xfsaild_wakeup(mp->m_ail, threshold_lsn);
98 }
99 }
100
101 /*
102 * AIL traversal cursor initialisation.
103 *
104 * The cursor keeps track of where our current traversal is up
105 * to by tracking the next ƣtem in the list for us. However, for
106 * this to be safe, removing an object from the AIL needs to invalidate
107 * any cursor that points to it. hence the traversal cursor needs to
108 * be linked to the struct xfs_ail so that deletion can search all the
109 * active cursors for invalidation.
110 *
111 * We don't link the push cursor because it is embedded in the struct
112 * xfs_ail and hence easily findable.
113 */
114 void
115 xfs_trans_ail_cursor_init(
116 struct xfs_ail *ailp,
117 struct xfs_ail_cursor *cur)
118 {
119 cur->item = NULL;
120 if (cur == &ailp->xa_cursors)
121 return;
122
123 cur->next = ailp->xa_cursors.next;
124 ailp->xa_cursors.next = cur;
125 }
126
127 /*
128 * Set the cursor to the next item, because when we look
129 * up the cursor the current item may have been freed.
130 */
131 STATIC void
132 xfs_trans_ail_cursor_set(
133 struct xfs_ail *ailp,
134 struct xfs_ail_cursor *cur,
135 struct xfs_log_item *lip)
136 {
137 if (lip)
138 cur->item = xfs_ail_next(ailp, lip);
139 }
140
141 /*
142 * Get the next item in the traversal and advance the cursor.
143 * If the cursor was invalidated (inidicated by a lip of 1),
144 * restart the traversal.
145 */
146 STATIC struct xfs_log_item *
147 xfs_trans_ail_cursor_next(
148 struct xfs_ail *ailp,
149 struct xfs_ail_cursor *cur)
150 {
151 struct xfs_log_item *lip = cur->item;
152
153 if ((__psint_t)lip & 1)
154 lip = xfs_ail_min(ailp);
155 xfs_trans_ail_cursor_set(ailp, cur, lip);
156 return lip;
157 }
158
159 /*
160 * Invalidate any cursor that is pointing to this item. This is
161 * called when an item is removed from the AIL. Any cursor pointing
162 * to this object is now invalid and the traversal needs to be
163 * terminated so it doesn't reference a freed object. We set the
164 * cursor item to a value of 1 so we can distinguish between an
165 * invalidation and the end of the list when getting the next item
166 * from the cursor.
167 */
168 STATIC void
169 xfs_trans_ail_cursor_clear(
170 struct xfs_ail *ailp,
171 struct xfs_log_item *lip)
172 {
173 struct xfs_ail_cursor *cur;
174
175 /* need to search all cursors */
176 for (cur = &ailp->xa_cursors; cur; cur = cur->next) {
177 if (cur->item == lip)
178 cur->item = (struct xfs_log_item *)
179 ((__psint_t)cur->item | 1);
180 }
181 }
182
183 /*
184 * Now that the traversal is complete, we need to remove the cursor
185 * from the list of traversing cursors. Avoid removing the embedded
186 * push cursor, but use the fact it is alway present to make the
187 * list deletion simple.
188 */
189 void
190 xfs_trans_ail_cursor_done(
191 struct xfs_ail *ailp,
192 struct xfs_ail_cursor *done)
193 {
194 struct xfs_ail_cursor *prev = NULL;
195 struct xfs_ail_cursor *cur;
196
197 done->item = NULL;
198 if (done == &ailp->xa_cursors)
199 return;
200 prev = &ailp->xa_cursors;
201 for (cur = prev->next; cur; prev = cur, cur = prev->next) {
202 if (cur == done) {
203 prev->next = cur->next;
204 break;
205 }
206 }
207 ASSERT(cur);
208 }
209
210 /*
211 * Return the item in the AIL with the current lsn.
212 * Return the current tree generation number for use
213 * in calls to xfs_trans_next_ail().
214 */
215 STATIC xfs_log_item_t *
216 xfs_trans_first_push_ail(
217 struct xfs_ail *ailp,
218 struct xfs_ail_cursor *cur,
219 xfs_lsn_t lsn)
220 {
221 xfs_log_item_t *lip;
222
223 lip = xfs_ail_min(ailp);
224 xfs_trans_ail_cursor_set(ailp, cur, lip);
225 if (lsn == 0)
226 return lip;
227
228 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
229 if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0) {
230 xfs_trans_ail_cursor_set(ailp, cur, lip);
231 return lip;
232 }
233 }
234
235 return NULL;
236 }
237
238 /*
239 * Function that does the work of pushing on the AIL
240 */
241 long
242 xfsaild_push(
243 struct xfs_ail *ailp,
244 xfs_lsn_t *last_lsn)
245 {
246 long tout = 1000; /* milliseconds */
247 xfs_lsn_t last_pushed_lsn = *last_lsn;
248 xfs_lsn_t target = ailp->xa_target;
249 xfs_lsn_t lsn;
250 xfs_log_item_t *lip;
251 int flush_log, count, stuck;
252 xfs_mount_t *mp = ailp->xa_mount;
253 struct xfs_ail_cursor *cur = &ailp->xa_cursors;
254
255 spin_lock(&mp->m_ail_lock);
256 xfs_trans_ail_cursor_init(ailp, cur);
257 lip = xfs_trans_first_push_ail(ailp, cur, *last_lsn);
258 if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
259 /*
260 * AIL is empty or our push has reached the end.
261 */
262 xfs_trans_ail_cursor_done(ailp, cur);
263 spin_unlock(&mp->m_ail_lock);
264 last_pushed_lsn = 0;
265 return tout;
266 }
267
268 XFS_STATS_INC(xs_push_ail);
269
270 /*
271 * While the item we are looking at is below the given threshold
272 * try to flush it out. We'd like not to stop until we've at least
273 * tried to push on everything in the AIL with an LSN less than
274 * the given threshold.
275 *
276 * However, we will stop after a certain number of pushes and wait
277 * for a reduced timeout to fire before pushing further. This
278 * prevents use from spinning when we can't do anything or there is
279 * lots of contention on the AIL lists.
280 */
281 tout = 10;
282 lsn = lip->li_lsn;
283 flush_log = stuck = count = 0;
284 while ((XFS_LSN_CMP(lip->li_lsn, target) < 0)) {
285 int lock_result;
286 /*
287 * If we can lock the item without sleeping, unlock the AIL
288 * lock and flush the item. Then re-grab the AIL lock so we
289 * can look for the next item on the AIL. List changes are
290 * handled by the AIL lookup functions internally
291 *
292 * If we can't lock the item, either its holder will flush it
293 * or it is already being flushed or it is being relogged. In
294 * any of these case it is being taken care of and we can just
295 * skip to the next item in the list.
296 */
297 lock_result = IOP_TRYLOCK(lip);
298 spin_unlock(&mp->m_ail_lock);
299 switch (lock_result) {
300 case XFS_ITEM_SUCCESS:
301 XFS_STATS_INC(xs_push_ail_success);
302 IOP_PUSH(lip);
303 last_pushed_lsn = lsn;
304 break;
305
306 case XFS_ITEM_PUSHBUF:
307 XFS_STATS_INC(xs_push_ail_pushbuf);
308 IOP_PUSHBUF(lip);
309 last_pushed_lsn = lsn;
310 break;
311
312 case XFS_ITEM_PINNED:
313 XFS_STATS_INC(xs_push_ail_pinned);
314 stuck++;
315 flush_log = 1;
316 break;
317
318 case XFS_ITEM_LOCKED:
319 XFS_STATS_INC(xs_push_ail_locked);
320 last_pushed_lsn = lsn;
321 stuck++;
322 break;
323
324 case XFS_ITEM_FLUSHING:
325 XFS_STATS_INC(xs_push_ail_flushing);
326 last_pushed_lsn = lsn;
327 stuck++;
328 break;
329
330 default:
331 ASSERT(0);
332 break;
333 }
334
335 spin_lock(&mp->m_ail_lock);
336 /* should we bother continuing? */
337 if (XFS_FORCED_SHUTDOWN(mp))
338 break;
339 ASSERT(mp->m_log);
340
341 count++;
342
343 /*
344 * Are there too many items we can't do anything with?
345 * If we we are skipping too many items because we can't flush
346 * them or they are already being flushed, we back off and
347 * given them time to complete whatever operation is being
348 * done. i.e. remove pressure from the AIL while we can't make
349 * progress so traversals don't slow down further inserts and
350 * removals to/from the AIL.
351 *
352 * The value of 100 is an arbitrary magic number based on
353 * observation.
354 */
355 if (stuck > 100)
356 break;
357
358 lip = xfs_trans_ail_cursor_next(ailp, cur);
359 if (lip == NULL)
360 break;
361 lsn = lip->li_lsn;
362 }
363 xfs_trans_ail_cursor_done(ailp, cur);
364 spin_unlock(&mp->m_ail_lock);
365
366 if (flush_log) {
367 /*
368 * If something we need to push out was pinned, then
369 * push out the log so it will become unpinned and
370 * move forward in the AIL.
371 */
372 XFS_STATS_INC(xs_push_ail_flush);
373 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
374 }
375
376 if (!count) {
377 /* We're past our target or empty, so idle */
378 tout = 1000;
379 } else if (XFS_LSN_CMP(lsn, target) >= 0) {
380 /*
381 * We reached the target so wait a bit longer for I/O to
382 * complete and remove pushed items from the AIL before we
383 * start the next scan from the start of the AIL.
384 */
385 tout += 20;
386 last_pushed_lsn = 0;
387 } else if ((stuck * 100) / count > 90) {
388 /*
389 * Either there is a lot of contention on the AIL or we
390 * are stuck due to operations in progress. "Stuck" in this
391 * case is defined as >90% of the items we tried to push
392 * were stuck.
393 *
394 * Backoff a bit more to allow some I/O to complete before
395 * continuing from where we were.
396 */
397 tout += 10;
398 }
399 *last_lsn = last_pushed_lsn;
400 return tout;
401 } /* xfsaild_push */
402
403
404 /*
405 * This is to be called when an item is unlocked that may have
406 * been in the AIL. It will wake up the first member of the AIL
407 * wait list if this item's unlocking might allow it to progress.
408 * If the item is in the AIL, then we need to get the AIL lock
409 * while doing our checking so we don't race with someone going
410 * to sleep waiting for this event in xfs_trans_push_ail().
411 */
412 void
413 xfs_trans_unlocked_item(
414 xfs_mount_t *mp,
415 xfs_log_item_t *lip)
416 {
417 xfs_log_item_t *min_lip;
418
419 /*
420 * If we're forcibly shutting down, we may have
421 * unlocked log items arbitrarily. The last thing
422 * we want to do is to move the tail of the log
423 * over some potentially valid data.
424 */
425 if (!(lip->li_flags & XFS_LI_IN_AIL) ||
426 XFS_FORCED_SHUTDOWN(mp)) {
427 return;
428 }
429
430 /*
431 * This is the one case where we can call into xfs_ail_min()
432 * without holding the AIL lock because we only care about the
433 * case where we are at the tail of the AIL. If the object isn't
434 * at the tail, it doesn't matter what result we get back. This
435 * is slightly racy because since we were just unlocked, we could
436 * go to sleep between the call to xfs_ail_min and the call to
437 * xfs_log_move_tail, have someone else lock us, commit to us disk,
438 * move us out of the tail of the AIL, and then we wake up. However,
439 * the call to xfs_log_move_tail() doesn't do anything if there's
440 * not enough free space to wake people up so we're safe calling it.
441 */
442 min_lip = xfs_ail_min(mp->m_ail);
443
444 if (min_lip == lip)
445 xfs_log_move_tail(mp, 1);
446 } /* xfs_trans_unlocked_item */
447
448
449 /*
450 * Update the position of the item in the AIL with the new
451 * lsn. If it is not yet in the AIL, add it. Otherwise, move
452 * it to its new position by removing it and re-adding it.
453 *
454 * Wakeup anyone with an lsn less than the item's lsn. If the item
455 * we move in the AIL is the minimum one, update the tail lsn in the
456 * log manager.
457 *
458 * This function must be called with the AIL lock held. The lock
459 * is dropped before returning.
460 */
461 void
462 xfs_trans_update_ail(
463 xfs_mount_t *mp,
464 xfs_log_item_t *lip,
465 xfs_lsn_t lsn) __releases(mp->m_ail_lock)
466 {
467 xfs_log_item_t *dlip=NULL;
468 xfs_log_item_t *mlip; /* ptr to minimum lip */
469
470 mlip = xfs_ail_min(mp->m_ail);
471
472 if (lip->li_flags & XFS_LI_IN_AIL) {
473 dlip = xfs_ail_delete(mp->m_ail, lip);
474 ASSERT(dlip == lip);
475 xfs_trans_ail_cursor_clear(mp->m_ail, dlip);
476 } else {
477 lip->li_flags |= XFS_LI_IN_AIL;
478 }
479
480 lip->li_lsn = lsn;
481 xfs_ail_insert(mp->m_ail, lip);
482
483 if (mlip == dlip) {
484 mlip = xfs_ail_min(mp->m_ail);
485 spin_unlock(&mp->m_ail_lock);
486 xfs_log_move_tail(mp, mlip->li_lsn);
487 } else {
488 spin_unlock(&mp->m_ail_lock);
489 }
490
491
492 } /* xfs_trans_update_ail */
493
494 /*
495 * Delete the given item from the AIL. It must already be in
496 * the AIL.
497 *
498 * Wakeup anyone with an lsn less than item's lsn. If the item
499 * we delete in the AIL is the minimum one, update the tail lsn in the
500 * log manager.
501 *
502 * Clear the IN_AIL flag from the item, reset its lsn to 0, and
503 * bump the AIL's generation count to indicate that the tree
504 * has changed.
505 *
506 * This function must be called with the AIL lock held. The lock
507 * is dropped before returning.
508 */
509 void
510 xfs_trans_delete_ail(
511 xfs_mount_t *mp,
512 xfs_log_item_t *lip) __releases(mp->m_ail_lock)
513 {
514 xfs_log_item_t *dlip;
515 xfs_log_item_t *mlip;
516
517 if (lip->li_flags & XFS_LI_IN_AIL) {
518 mlip = xfs_ail_min(mp->m_ail);
519 dlip = xfs_ail_delete(mp->m_ail, lip);
520 ASSERT(dlip == lip);
521 xfs_trans_ail_cursor_clear(mp->m_ail, dlip);
522
523
524 lip->li_flags &= ~XFS_LI_IN_AIL;
525 lip->li_lsn = 0;
526
527 if (mlip == dlip) {
528 mlip = xfs_ail_min(mp->m_ail);
529 spin_unlock(&mp->m_ail_lock);
530 xfs_log_move_tail(mp, (mlip ? mlip->li_lsn : 0));
531 } else {
532 spin_unlock(&mp->m_ail_lock);
533 }
534 }
535 else {
536 /*
537 * If the file system is not being shutdown, we are in
538 * serious trouble if we get to this stage.
539 */
540 if (XFS_FORCED_SHUTDOWN(mp))
541 spin_unlock(&mp->m_ail_lock);
542 else {
543 xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp,
544 "%s: attempting to delete a log item that is not in the AIL",
545 __func__);
546 spin_unlock(&mp->m_ail_lock);
547 xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
548 }
549 }
550 }
551
552
553
554 /*
555 * Return the item in the AIL with the smallest lsn.
556 * Return the current tree generation number for use
557 * in calls to xfs_trans_next_ail().
558 */
559 xfs_log_item_t *
560 xfs_trans_first_ail(
561 struct xfs_mount *mp,
562 struct xfs_ail_cursor *cur)
563 {
564 xfs_log_item_t *lip;
565 struct xfs_ail *ailp = mp->m_ail;
566
567 lip = xfs_ail_min(ailp);
568 xfs_trans_ail_cursor_set(ailp, cur, lip);
569
570 return lip;
571 }
572
573 /*
574 * Grab the next item in the AIL from the cursor passed in.
575 */
576 xfs_log_item_t *
577 xfs_trans_next_ail(
578 struct xfs_mount *mp,
579 struct xfs_ail_cursor *cur)
580 {
581 struct xfs_ail *ailp = mp->m_ail;
582
583 return xfs_trans_ail_cursor_next(ailp, cur);
584 }
585
586
587 /*
588 * The active item list (AIL) is a doubly linked list of log
589 * items sorted by ascending lsn. The base of the list is
590 * a forw/back pointer pair embedded in the xfs mount structure.
591 * The base is initialized with both pointers pointing to the
592 * base. This case always needs to be distinguished, because
593 * the base has no lsn to look at. We almost always insert
594 * at the end of the list, so on inserts we search from the
595 * end of the list to find where the new item belongs.
596 */
597
598 /*
599 * Initialize the doubly linked list to point only to itself.
600 */
601 int
602 xfs_trans_ail_init(
603 xfs_mount_t *mp)
604 {
605 struct xfs_ail *ailp;
606 int error;
607
608 ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
609 if (!ailp)
610 return ENOMEM;
611
612 ailp->xa_mount = mp;
613 INIT_LIST_HEAD(&ailp->xa_ail);
614 error = xfsaild_start(ailp);
615 if (error)
616 goto out_free_ailp;
617 mp->m_ail = ailp;
618 return 0;
619
620 out_free_ailp:
621 kmem_free(ailp);
622 return error;
623 }
624
625 void
626 xfs_trans_ail_destroy(
627 xfs_mount_t *mp)
628 {
629 struct xfs_ail *ailp = mp->m_ail;
630
631 xfsaild_stop(ailp);
632 kmem_free(ailp);
633 }
634
635 /*
636 * Insert the given log item into the AIL.
637 * We almost always insert at the end of the list, so on inserts
638 * we search from the end of the list to find where the
639 * new item belongs.
640 */
641 STATIC void
642 xfs_ail_insert(
643 struct xfs_ail *ailp,
644 xfs_log_item_t *lip)
645 /* ARGSUSED */
646 {
647 xfs_log_item_t *next_lip;
648
649 /*
650 * If the list is empty, just insert the item.
651 */
652 if (list_empty(&ailp->xa_ail)) {
653 list_add(&lip->li_ail, &ailp->xa_ail);
654 return;
655 }
656
657 list_for_each_entry_reverse(next_lip, &ailp->xa_ail, li_ail) {
658 if (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0)
659 break;
660 }
661
662 ASSERT((&next_lip->li_ail == &ailp->xa_ail) ||
663 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0));
664
665 list_add(&lip->li_ail, &next_lip->li_ail);
666
667 xfs_ail_check(ailp, lip);
668 return;
669 }
670
671 /*
672 * Delete the given item from the AIL. Return a pointer to the item.
673 */
674 /*ARGSUSED*/
675 STATIC xfs_log_item_t *
676 xfs_ail_delete(
677 struct xfs_ail *ailp,
678 xfs_log_item_t *lip)
679 /* ARGSUSED */
680 {
681 xfs_ail_check(ailp, lip);
682
683 list_del(&lip->li_ail);
684
685 return lip;
686 }
687
688 /*
689 * Return a pointer to the first item in the AIL.
690 * If the AIL is empty, then return NULL.
691 */
692 STATIC xfs_log_item_t *
693 xfs_ail_min(
694 struct xfs_ail *ailp)
695 /* ARGSUSED */
696 {
697 if (list_empty(&ailp->xa_ail))
698 return NULL;
699
700 return list_first_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
701 }
702
703 /*
704 * Return a pointer to the item which follows
705 * the given item in the AIL. If the given item
706 * is the last item in the list, then return NULL.
707 */
708 STATIC xfs_log_item_t *
709 xfs_ail_next(
710 struct xfs_ail *ailp,
711 xfs_log_item_t *lip)
712 /* ARGSUSED */
713 {
714 if (lip->li_ail.next == &ailp->xa_ail)
715 return NULL;
716
717 return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
718 }
719
720 #ifdef DEBUG
721 /*
722 * Check that the list is sorted as it should be.
723 */
724 STATIC void
725 xfs_ail_check(
726 struct xfs_ail *ailp,
727 xfs_log_item_t *lip)
728 {
729 xfs_log_item_t *prev_lip;
730
731 if (list_empty(&ailp->xa_ail))
732 return;
733
734 /*
735 * Check the next and previous entries are valid.
736 */
737 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
738 prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
739 if (&prev_lip->li_ail != &ailp->xa_ail)
740 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
741
742 prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail);
743 if (&prev_lip->li_ail != &ailp->xa_ail)
744 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0);
745
746
747 #ifdef XFS_TRANS_DEBUG
748 /*
749 * Walk the list checking lsn ordering, and that every entry has the
750 * XFS_LI_IN_AIL flag set. This is really expensive, so only do it
751 * when specifically debugging the transaction subsystem.
752 */
753 prev_lip = list_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
754 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
755 if (&prev_lip->li_ail != &ailp->xa_ail)
756 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
757 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
758 prev_lip = lip;
759 }
760 #endif /* XFS_TRANS_DEBUG */
761 }
762 #endif /* DEBUG */
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